Polk County buys newfangled cover crop tractor for upstream farmers

A central Iowa partnership has emerged to encourage the use of cover crops in farm fields in the watersheds of the Des Moines and Raccoon rivers in an effort to boost the quality of the metro’s major sources of drinking water.

Polk County will buy a $600,000 tractor that is tall enough to straddle rows of corn and apply cover-crop seed during the summer while the corn is still growing. It’s a cutting-edge technique that is expected to yield better success with the cover crops, which are used to reduce soil erosion and flooding, boost soil quality and help limit fertilizer and chemical seepage into rivers. The seeds are often applied after harvest when the available time to take root is limited by the end of the growing season.

“Our hope is for the machine to travel around and get some excitement,” said John Swanson, watershed management authority coordinator for Polk County. “As soon as you see the corn harvested, you’re going to see that nice lush cover.”

Polk County is using about $150,000 of federal pandemic relief money to help pay for the machine. The city of Des Moines and Des Moines Water Works are contributing $75,000 and $25,000, respectively, and the Iowa Department of Agriculture and Land Stewardship is contributing up to $350,000, depending on how much is planted.

“Our public and private partners are critical to the success of every conservation project underway in Iowa,” said Mike Naig, the state’s secretary of agriculture.

Heartland Co-op has agreed to use the new machine to apply seed to fields in the Beaver Creek watershed, which feeds the Des Moines River. Swanson hopes to cover about 10,000 acres this year in Boone and Greene counties.

Members of the Central Iowa Cover Crop Seeder Project worked with John Deere in the past year to fine-tune a demonstrational version of the machine, he said, with the hope to make it more widely available. Previously, farmers have customized tractors used to spray fields, with their tall tires and collapsible booms that span many rows at once.

The new machine is capable of planting a variety of cover crops, including rye, oats, turnips and radishes.

“It’s going to be one of the first ones in Iowa out there,” Swanson said.

Farmers will pay a yet-to-be-determined fee to take part in the project. It costs about $40 per acre to seed the cover crops, Swanson said, but there are federal and state programs that offer money to farmers who start planting the crops. The goal is to cover 40,000 acres in four years and expand the program to other parts of the Des Moines and Raccoon watersheds, which stretch into far northern Iowa.

The idea came from northern Kansas, where state and city officials teamed with a nonprofit conservation organization to buy eight similar machines to lay cover crops in watersheds that feed Wichita’s drinking water sources. That partnership got national recognition in 2020 from the US Environmental Protection Agency.

“What happens upstream impacts the safety of our drinking water and the recreation in our rivers and lakes for everyone in Polk County,” said Angela Connolly, chairperson of the county’s board of supervisors. “We know the utilization of reducing cover crops can have a tremendous impact on nutrient load from agricultural operations in our surface water and groundwater and improve soil health.”

The project is also meant to sow good will with upstream farmers who were alienated by a water-quality court fight from 2015, when Des Moines Water Works sued three northwest Iowa counties for high levels of nitrate it had to remove from Raccoon River water. Crop fertilizer is a source of the contaminant.

“We recognize the value this project can have in sharing some of the responsibility to protect our public waterways and watersheds,” said Ted Corrigan, chief executive of the water utility.

Cover crops are a key component of the state’s Nutrient Reduction Strategy, which promotes voluntary measures for farmers to keep their fertilizers from waterways. State agriculture officials said cover crops have been planted on more than 2 million acres of land in recent years.

Iowa farmers plant more than 20 million acres of corn and soybeans, according to recent figures from the US Department of Agriculture.

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